The present invention relates to a character display circuit having the function to display a character by superimposing a character code on a video signal and a method for character display, and more particularly to a character display circuit and method having the function to generate a character display timing signal referenced to vertical and horizontal synchronizing signals of a video signal and the function to generate, as part of the character display timing signal, a character code which conforms to a VBI (video blanking interval) code format used to perform closed captioning by superimposing the character code during the blanking period of the video signal.
Conventionally, a character display circuit for generating a character display timing signal referenced to vertical and horizontal synchronizing signals of a video signal and displaying a character pattern on a television screen and a VBI character coder used for closed captioning are constructed in the form of separate circuits.
For example, M35040 manufactured by Mitsubishi Denki is a commercially available character display circuit. On the other hand, CX-7907A manufactured by Sony is a commercially available character coding circuit utilizing the vertical blanking period as in the case of a character broadcast signal.
A known example of a technique utilizing character broadcast is described in JP-A-2-91875.
In some of VTRs for business use, a character display circuit and a VBI character coder are provided separately and a closed caption signal is superimposed during the blanking period of a video signal when recording is carried out by using the VTR. Through this, when a closed caption decoder is installed in a TV, a caption can be reproduced, on the TV side, from a signal reproduced by the VTR. For example, with a date/time of recording superimposed on a video signal, the date/time of video recording can be displayed as a caption on the TV screen at any time and the caption can be erased as necessary. Accordingly, in contrast to the case where a display character is superimposed directly on image data, the recorded picture will not be hindered.
Additionally, the VBI character coder provided for the VTR is used for superimposition of digital data generated concomitantly with the recorded picture such as absolute addresses on the tape and editing control marks.
But, due to the fact that the character display circuit and the VBI character coder are constructed in the form of separate circuits, there arises a problem that the circuit configuration is complicated.